As miniaturization and compactness for an element having high performance are constantly demanded, a technique for producing high density nanopatterns by further reducing a pitch size of patterns, for example, a line width of patterns (critical dimension, CD) and spacing between patterns for implementing more patterns in a limited area is required.
As one method for forming nanopatterns, a photolithography technique in a top-down manner may be exemplified. However, the photolithography technique is limited in improving resolution due to the wavelength of a light source, the resolution limitation of an optical system and the like.
As one of the efforts for overcoming resolution limitation in the photolithography technique and developing next-generation micromachining technology, a directed self-assembly (DSA) technique in a bottom-up manner using the self-assembly of molecules is receiving attention (Korean Patent Laid-Open Publication No. 10-2016-0073408).
The DSA technique has merits of being relatively simple, capable of forming high density patterns as compared with a conventional photolithography technique, and capable of forming a periodically arranged structure such as a sphere, a cylinder or a lamella shape by phase separation of a block copolymer.
However, the block copolymers suggested so far have rather low etching selectivity between each block to destroy patterns, or to have difficulty in reducing the line width of patterns to below a certain level, and have rather a lot of defects in LER (line edge roughness), LWR (line width roughness) and the like to degrade the quality of a semiconductor device.
Accordingly, there is currently a need to develop a block copolymer having excellent etching selectivity and being capable of minimizing LER and LWR to form high quality nanopatterns.